Vania



G. HARLOW.

TRANsroRmER.

APPLICATION FILED JUNE 20. i916.

Patented' July 29, 1912).

INVENTOR WITNESSES ATTORNEY GEORGE HARLOW, OF ALTRINCHAM, ENGLAND,

ASSIGNOR T0 WESTINGHOUSE ELECTRIC MANUFACTURING COMPANY, A CORPORATIONOF PENNSYL- VANIA.

TRANSFORMEB.

Specication of Letters Patent.

Patented July 29, 1919.

.Application led J une 20, 1916. Serial No. 104,794.

To all LU/wm z't may concern."

Be it known that I, GEORGE HARLow, a subject of the King of GreatBritain, and a resident of IVoodgarth, Oldfield Road, Altrincham, in thecounty of Chester, England, have invented a new and useful Improvementin Transformers, of which the following is a specification.

My invention relates to electrical transf formers and particularly tocore-type transformers in which the coils that constitute the windingsare braced to resist permanent displacement resulting from any axialstresses that may be imposed upon them.

In core-type transformers, it is usual to wind the low-tension windinginto a single coil for each core le and to dispose this coil closelyadjacent to t ie iron core. The hightension winding is usually woundinto a number of coils which are placed outside of the low-tension coilsand arranged coaxially therewith. These high-tension coils, beingsuperposed upon one another, are spaced from one another by means-ofinsulating blocks or insulating washers. If a short circuit occurs onthe low-tension side of the transformer, in addition to the very heavyradial stresses set up between the windings, axial stresses aregenerated which tend to force the high-tension coils apart. Of course,axial stresses are imposed upon the low-tension coils which may bedistorted also, but usually are Inot because of their form ofconstruction. In order to secure the coils against axial movement and toresist the axial stresses that result from short circuits. it has beenusual to provide heavy clamps at the top and bottom of the member tobrace the coils against forces that may permanently displace them. It isfound, however, that., although these clamps may be forced tightlyagainst the coils when the transformer is built, the coils graduallybecome loosened after the transformer has been placed in service becauseof the shrinkage of the insulating material. IVhen the high-tensionwinding is composed of a large number of superimposed coils, this defectis especially noticeable.

According to 'the present invention. I provide means whereby the coilsmay be securely clamped under all conditions and which automaticallycompensates for any slackness resulting from the shrinkage of theinsulating material. My clamping means permits the coils to be axiallymoved when subjected to axial stresses that, under ordinary conditions,would be dangerous to them. After the axial stresses have subsided, thecoils are returned to their original position and firmly held inalinement. Moreover, any axial movement that the coils may partake of isdamped in such manner as to preclude them from being suddenly pulledapart.

For a better understanding of the nature and scope of my invention,reference may be had to the following description and the accompanyingdrawing in which Figure 1 is a sectional view of the upper part of acoretype transformer embodying a formv of my invention, and Fig. 2is asimilar view of a modified form of the structure shown in F ig.' 1.

Referring to the figures, a core leg 1 of a core-type transformer isembraced by a low-tension winding 2 which, in this instance, consists ofa single coil for each core leg, and a high-tension winding whichconsists of a number of superposed coils 3. The low-tension winding 2 isspaced from the core leg 1 by means of an insulating barrier l and isseparated from thc high-tension coils 3 by means of an insulatingbarrier Each coil 3 is provided with a suitable-insulating covering 6which usually consists of a wrapping of impregnated tape or otherinsulating material.

In Fig. 1, the core member of the transformer is provided with two anglepieces 7 and 8 which are connected by a bolt 9 to clamp the yoke or topportion of the core member. Each of the angle pieces 7 and 8 is providedwith a bolt 10 that is engaged by a lock nut 11. The shank of the bolt10 projects into an opening providedin a head member 12. On top of theuppermost hightension coil 3 is placed a plurality of insulating washers13 and a steel ring 1i which is slit in any suitable manner to preventthe circulation of eddy currents therein. Interposed between the head l2and the steel ring 14 is a spacing member 15 ipon which is formed aflanged portion 16 that is alined with the head 12. A compressionspring. 17 is interposed between the iianged portion of the head 12 anda flanged portion 16 of the spacing member 15. The spacing member 15 isprovided also with an upwardly extending portion 18 that projects into,and forms a piston member to coperate with, a downwardly-extendingcylinder -19 that is formed integrally with the head member 12. Thepiston member 18 and the cylinder '19 constitute a dash pot which issurrounded by the compression spring 17. Holes 20,

formed in the upper walls of the dash pot, provide means for regulatingthe damping eli'ect for which the dash pot is furnished by allowing theoil in which the whole mechanismis immersed to pass into 'and out of thedash pot cylinders. Of course, it will be understood that the dash potsand compression springs permitithe high-tension coils to be axiallydisplaced but their movement is damped which precludes them from beingrapidly separated when the transformer is subjected to any abnormalstresses. The springs 17 compensate for the shrinkage in the insulationand, under normal conditions, firmly hold the coils in fixedrelationship. Any suitable number of dash pots and springs may beprovided, depending upon the size of the transformer coils and thenecessity for maintaining a substantially uniform compression upon them.v

In assembling the transformer, the bolts 10 are tightened up, therebyfirmly holding the coils by compressing the spring members 17 and addinga suliicient number of insulating washers 13. The spacing member 15 .isso designed as not to affect or restrain the action of the dash pot and,therefore, suiicient room must be provided between the head of thecylinder and the top of the piston member 18. When the insulationshrinks, it is com ensated for by the springs 17, but any su den axialmovement of the coils resulting from heavy magnetic stresses will beprevented by means of the dash pots,l since the oil contained in thecylinders 19 will be prevented from escaping too quickly from them byreason of the comparatively small diameters of the exit holes 20. If thewhole transformer is not immersed in oil, the dash pots will have adamping action by reason of the compression of the air contained inthecylinders 1 9.

In Fig. 2, I havexshow thecompression springs 17 and the dash potmembers 18 and 19 placed intermediate the coils 3. The adjacent coils 3are separated by the compression springs 17 located between split rings21. and 22, and are held in place by means ofthe cylinders 19 which, asmentioned above, coact with the piston members '18 65y `upper ring 21.The compression of thesprings 17 may be adjusted when the trans-' 'ithat, in this instance, are threaded into the former is being assembledby means of the usual clamping means at the top Aand bottom of thetransformer core-members.

In the foregoing description, I have shown my invention applied tothehightension windings only of the transformer,

but it will be appreciated that a similar structure may be provided forthe lowtension winding.

Although I have shown only one form of my invention, it will beunderstood that` many modifications may be made without.A

departing from the spirit and scope of the appended claims.

'I claim as my invention: A

1. A transformer comprising a core member, current-carrying coilsinductively related thereto, elastic means for normally holding andurging said coils together and means for substantially preventingyielding vmovement of said elastic means when sudden mechanical stressesare imposed on said coils. v

2. A transformer comprising a core inember, current-carrying coilsinductively related tliereto, elastic means for normally holding saidcoils in fixed relationship, and retarding means for substantiallypreventing yielding movement of said elastic means l in a reversedirection from that in which the coils are normally urged, lwhen suddenj mechanical stresses are imposed on said coils:

3. A transformer comprising a core member, current-carrying coilslinductively related thereto, elastic means for normally holding andurgin said coils together, and

a dash-pot mechanism which, when. sudden mechanical stresses are imposedon said coils, substantially prevents yielding movement in a reversedirection from that in whichsaid coils are normally urged.

4. A transformer comprising a core member and a plurality ofsuperimposed currentcarrying coils that are subjected to magneticstresses directedin axial directions, yielding members for normallyholding the coils in firm engagement with one another but permittingthem to move temporarily in axial directions to resist the imposed`magnetic stresses, and means for retarding the com-V pressive action ofthe springs to preclude abrupt separation of the coils.

5. A transformer comprising a core member, current-carrying coilstherefor that are subjected to axial magnetic stresses, springs held incompression for normally holding the coils in fixed relationship topermit them tomove axially when subjected to abnormal, stresses, anddash pots enveloped by saidv springs for retarding the axial movement ofsubscribed my name this nineteenth day of the coils, whereby the motionof a coil in May, 1916. response to a slowly applied force is permittedbut the motion occasioned by a sud- GEORGE HARLOW 5 denly applied forceis substantially nega- Witnesses: tived. W. S. Torus,

In testimony whereof, I have hereunto E. JACKSON.

